Yes, verified by candling. What do I do about the humidity since my chicken eggs and duck eggs are at different stages of development and have different requirements?
You'll have to increase it, so that the ducklings can hatch. You can lower the humidity again once they're done to try to get the chicken eggs to catch up on moisture loss if they fall behind. But they should be okay; humidity is more important as an average across the entire incubation period, and a few days of higher humidity shouldn't hurt the other eggs.